Why did dinosaurs become extinct?

New understanding of dinosaur extinction dinosaurs have been extinct for tens of millions of years, but we can still see them alive in movies and TV. How do paleontologists infer their life forms from paleontological fossils? Neopaleontologists try to make the image of dinosaurs closer to the truth by using various technologies such as computers and biological analogy. In a swamp in central Florida, scientists are studying the behavior of alligators. The purpose of scientists' research is not the alligator itself, but to study its extinct "close relatives"-dinosaurs through its living habits. This crocodile is more than four meters long and is a real big guy. Its last tail has been lost in the struggle with its own kind, but it is still very strong. Four researchers rode on crocodiles. They want to study how alligators throw people on their backs. The flexibility of alligator's body is amazing. When it shakes its body violently, it can be compared with the best rubber. A scientist is standing a few meters away from the crocodile with a plastic rope in his hand. One end of the plastic rope is connected with a dish-shaped force converter, which is used to test the great strength of the crocodile when it bites hard. The researchers covered the crocodile's nostrils and eyes with towels and tape. After a while, when the researchers suddenly took them off, the alligator would exhale desperately and open its eyes wide, so that the researchers would record the characteristics of the alligator's breathing and the movement of the eye muscles. It is estimated that this alligator will emit the force equivalent to 1400 kg of gravity when it bites hard, which is quite amazing, that is to say, it can easily break the spine of a cow. The biting behavior of alligators is of great significance for scientists to study the predatory behavior of Tyrannosaurus Rex (a fierce carnivorous dinosaur). Paleontological research is no longer limited to fossils. Because dinosaurs have been extinct forever in this world, it is very difficult for paleontologists to study the living habits of dinosaurs. Of course, fossils are a very important research approach, but it is far from enough to be limited to fossils. Now, many paleontologists have begun to study dinosaurs in many novel ways and made good progress. Instead of spending the whole summer dealing with dusty fossils, the new school of paleontologists began to infer the behavior characteristics of dinosaurs by studying the behavior characteristics of existing organisms in laboratories or field experiments. For example, they will put pigeons in a wind tunnel and study the evolution from dinosaurs to birds by studying the flight behavior of pigeons. Or they will input the image of dinosaur bones into the computer, and infer the movement mode of dinosaurs by comparing it with the existing large animal bones. These new paleontologists are not limited to the old paleontologists, but only satisfied with classifying dinosaurs and splicing different kinds of dinosaur skeleton fossils. Their goal is to make dinosaurs "live". This technology is more and more widely used in film shooting. Now some of the topics they are studying are: were large dinosaurs clumsy or very agile? What do they eat? Are they gregarious or solitary? Do they feed their offspring themselves? How long can they live? Will they get bigger and bigger with age? Do they have a special physiological system to attract the opposite sex? How did they evolve a team that learned to fly? Wait a minute. These new paleontologists are divided into many tribes, and their research angles are different, from evolutionary biology, zoology to physiology and so on. They also use various tools, including computers, CT scanners, X-rays and electron microscopes. The topics of their research papers are very small, such as explaining the position of dinosaur nostrils or the function of nose, or studying how a muscle of dinosaur head moves. Tyrannosaurus rex is a scavenger? Although the field research on dinosaur fossils still occupies a dominant position in this research field, at present, more and more new scientists question the practice of inferring dinosaur habits by relying on bones. Legendary paleontologist Jack Horney said, "In the past 20 years, we have become accustomed to drawing conclusions based on very little evidence, but in fact, those conclusions are far from the truth." Honey 199 1 put forward a controversial theory. He thinks that Tyrannosaurus Rex, known as the "killer among killers", is actually just a "scavenger"-it only eats dead animals. Horney believes that the banana-sized teeth of Tyrannosaurus Rex are not used to chew the meat of living animals, but to crush the bones of corpses. Obviously, according to Horney, the fierce Tyrannosaurus Rex suddenly became a giant "vulture". Honeye failed to convince contemporary scientists that it is sometimes difficult to distinguish scavengers from carnivores. Jackals, for example, eat both carrion and living things. Using analogy to restore the dinosaur's head, the laboratory of Ohio University in the United States preserves the head bones of various animals, some of which are the skulls of extinct paleontologists and some of which are the skulls of existing animals. These are the research objects of Professor Levin Whitman. Professor Whitman added soft tissue to the dinosaur skull. He spent a lot of time studying the similarity between animals and restoring dinosaurs through this similarity. His research found that the physiological structure of dinosaurs that lived 248 million to 200 million years ago was very similar to that of alligators and seagulls that still exist today. Professor Whitman's recent theory has caused a new round of turmoil. He pointed out that the nostrils of dinosaur images widely appeared in movies and pictures were placed too high on their heads by artists. Professor Whitman spent several months studying the position of modern animals' nostrils. Then, he carefully studied the skeletal morphology of dinosaur head fossils and came to the conclusion that modern people misplaced the position of dinosaur nostrils, and the position of nostrils on the face should be lower and closer to the mouth. Whitman explained that the lower nostril position helped dinosaurs find potential food sources and decide whether it was worth opening their mouths to bite. Professor Whitman also studied another paleontologist's hypothesis: a dinosaur named Triceratops had cheeks like cows, horses and humans today. Former paleontologists believed that the function of cheeks was to hold food for dinosaurs to chew or chew. But in contrast, Whitman thinks that animals with cheeks are generally supported by bones, while Triceratops and other herbivorous dinosaurs have no cheeks supported by bones. Therefore, Whitman suggested that the facial morphology of Triceratops dinosaurs was actually more similar to the beaks of birds today. Herbivorous dinosaurs probably used this sharp beak to bite off young leaves from plants and then swallowed them whole without chewing. "They may have been chewed up in the stomach," said Professor Whitman. Small joint movement takes a lot of time. Professor Steven Gates of Brown University in the United States is another pioneer of the new school of dinosaur research. Professor Gators's research is very detailed. He will stay in front of the computer screen for a few days, studying a small lump on the toe of dinosaur fossils. He even spent months or even years studying the movement of dinosaur shoulder joints. Professor Jiatesi believes that dinosaurs are really complex animals, and studying their whole bodies is a huge project, so he can only start from a small place. In fact, Professor Gators' view is also the biggest feature of the whole new school of dinosaur research. Old-school dinosaur scientists are always obsessed with splicing the whole skeleton of dinosaurs. They are constantly looking for the lost dinosaur fossils in the wild. They put these fossils together, put the skeleton into the right shape, and then they began to announce, "I think dinosaurs walked like this." A new school of scholars, represented by Gattus, speculated the movement mode of dinosaurs by studying the evolution of dinosaur body details. We all know that there are flying dinosaurs, such as pterosaurs, but the research on how dinosaurs fly has just begun. Many people instinctively speculate about the flight of giant pterosaurs based on the flight of birds now, but this speculation is likely to go astray. How did flight evolve? Did the first flying dinosaur just glide like a glider or flap its wings? Did flight evolve from climbing? When dinosaurs travel on steep cliffs, the flapping of their arms will increase the upward traction. Researchers at the University of Montana in the United States studied the movement patterns of young birds, and they also gained upward traction by flapping their wings. 1975 dinosaur research enters film and television culture. Robert baker, a paleontologist from Harvard University, and John Ostrom from Yale University jointly published a controversial article, which overthrew many traditional scholars' descriptions of dinosaurs. They think dinosaurs are warm-blooded animals, not cold-blooded animals. They raised their offspring instead of being indifferent to their offspring like turtles and crocodiles. They also believe that dinosaurs lived in groups and hunted and migrated together. Baker and Ostrom also believe that birds are direct descendants of dinosaurs. The views of Baker and Ostrom have a great influence on the modern popular dinosaur view. The movie Jurassic Park, which we are familiar with, can be said to restore the dinosaur form according to Baker's point of view: dinosaurs flew around the grassland in droves to feed their offspring ... John Huggieson, a young scholar at Stanford University in the United States, further revised people's traditional understanding of dinosaurs. He tried to find the answer to this question: Can Tyrannosaurus Rex really run? If so, how fast can you run? Does it have such powerful hind leg muscles to support its huge body and drive at a high speed of 70 kilometers per hour? Hu Jisen thought that Tyrannosaurus Rex could not be so flexible. He used a computer to simulate the movement form of Tyrannosaurus rex, calculated the pressure on the skeleton of Tyrannosaurus rex at different speeds, and then came to this conclusion. Hu Jisen believes that if Tyrannosaurus Rex can run at a speed of 70 kilometers per hour, then two legs are not enough. Each leg bears 62% of the body weight of about 6 tons, and the strength of Tyrannosaurus Rex's leg bone can't be supported at all. The new explanation of dinosaur extinction The behavior of dinosaurs that fascinates paleontologists is how they became extinct. The scientific community has long had a simple but unsatisfactory explanation: the influence from outer space (such as falling meteorites) led to their extinction, and the whole process was very rapid, intense and effective: the earth was suddenly shaken by huge meteorites, giving off dazzling light and huge explosion shock waves, and dinosaurs withered like leaves after a storm. But this can't be the whole story. Professor filippo galli of university of alberta put forward a brand-new viewpoint based on his research on dinosaur habitats in North America. Gary believes that before and after the early extinction of dinosaurs, the earth experienced a very big environmental change, the sea level fell, and many closed spaces separated by seawater were connected at once. In this way, many species have the opportunity to communicate. For dinosaurs, the newly arrived species probably carried deadly microorganisms, which led to their massive deaths. Obviously, Gary's view can only explain the situation in North America, so this may be just one reason for the extinction of dinosaurs. In fact, all the reasons can be summed up in one point: the evolution of dinosaurs could not adapt to the drastic changes in the earth's environment. But how did this process happen? Neopaleontologists are studying every detail of the existence of dinosaurs, trying to outline a complete picture of the dinosaur era. Excerpt from: www.dkpart.com